Correct Answer and Feedback
Troubleshoot the electrical system.
When the directional control valve operates correctly manually
but not when energized by the rear door switch, this indicates
that an electrical problem exists and must be corrected. (Page
54, para 3)
Replace the shuttle valve.
The directional control valve and the
shuttle valve would cause
the stacker to raise roughly.
you already replaced the
directional control valve, the shuttle
valve is the component in
the hydraulic circuit that would cause
faulty operation and must
be replaced. (Page 62, para 10)